Deep brain stimulation lead

ABSTRACT

The present disclosure discusses a system and methods for a deep brain stimulation lead. More particularly, the disclosure discusses a stimulation lead that includes one or more silicon based barrier layers within a MEMS film. The silicon based barrier layers can improve device reliability and durability. The silicon based barrier layers can also improve adhesion between the layers of the MEMS film.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority as a continuation applicationunder 35 U.S.C. § 120 of U.S. patent application Ser. No. 16/551,390filed on Aug. 26, 2019, which claims priority as a continuationapplication under 35 U.S.C. § 120 of U.S. patent application Ser. No.16/015,625 filed on Jun. 22, 2018, which claims priority as acontinuation application under 35 U.S.C. § 120 of U.S. patentapplication Ser. No. 15/281,468 filed on Sep. 30, 2016, which claimspriority as a continuation application under 35 U.S.C. § 120 of U.S.patent application Ser. No. 14/470,423 filed on Aug. 27, 2014. Thecontents of the forgoing applications are herein incorporated byreference in their entirety.

BACKGROUND OF THE DISCLOSURE

Deep brain stimulation (DBS) is a neurostimulation therapy whichinvolves electrical stimulation systems that stimulate the human brainand body. DBS can be used to treat a number of neurological disorders.Typically DBS involves electrically stimulating a target area of thebrain.

SUMMARY OF THE DISCLOSURE

According to one aspect of the disclosure, a neurological lead includesa planar formed, cylindrical film that defines a lumen. The planarformed, cylindrical film includes a distal end, a proximal end, and aplurality of electrodes. The planar formed, cylindrical film can alsoinclude a ribbon cable extending from the distal end of the planarformed, cylindrical film into the lumen. The film can include aplurality of layers that can include a first polymeric layer, a firstsilicon based barrier layer at least partially disposed over the firstpolymeric layer, and a first metal layer at least partially disposedover the first silicon based barrier layer. Other layers can include asecond silicon based barrier layer at least partially disposed over thefirst metal layer or the first silicon based barrier layer. The secondsilicon based barrier layer can define a first plurality ofthrough-holes. Another layer can be a second polymeric layer that is atleast partially disposed over the second silicon based barrier layer.The second polymeric layer can define a second plurality of throughholes. The first plurality of through-holes is substantially alignedwith the second plurality of through holes to define each of theplurality of electrodes. The film can also include a second metal layerdisposed on the first metal layer.

In some implementations, the first metal layer can form the plurality ofelectrodes and a plurality of traces. The first metal layer can alsoform a plurality of contact pads disposed on the ribbon cable. Each ofthe plurality of contact pads are electrically coupled with at least oneof the plurality of electrodes by a trace formed in the first metallayer. The second metal layer can include gold and the first metal layercan include one of platinum and titanium.

The first and second silicon based barrier layers can include at leastone of Silicon Nitride, Silicon Oxide, Silicon Carbide, Polysilicon,Amorphous Silicon, Titanium Dioxide, and Titanium III Oxide. A thicknessof the first and second silicon based barrier layers can be betweenabout 100 nm and about 2 μm thick.

According to another aspect of the disclosure, a method of forming aneurological lead can include forming a planar film that includes aplurality of electrodes and a ribbon cable extending from a distal endthereof. Forming the film can include depositing a first silicon basedbarrier layer at least partially over a first polymeric layer anddepositing a first metal layer at least partially over the first siliconbased barrier layer. The method can also include depositing a secondsilicon based barrier layer partially over the first metal layer and thefirst silicon based barrier layer, and then depositing a secondpolymeric layer at least partially over the second silicon based barrierlayer. Forming the film can also include depositing a second metal layeron the first metal layer. The method to form the lead can also includeheating the formed planar film and molding the heated planar film into acylinder, which defines a lumen. The method can also include extendingthe ribbon cable into the lumen defined by the cylinder.

In some implementations, the method also includes forming the pluralityof electrodes and contact pads in the first metal layer. A plurality oftraces can electrically couple each of the plurality of contact pads toat least one of the plurality of electrodes. The method can also includedepositing the second metal layer on the plurality of contact pads. Eachof the plurality of electrodes can be defined by etching a plurality ofthrough holes in the second silicon based barrier layer and the secondpolymeric layer. The first and second silicon based barrier layers caninclude at least one of silicon nitride, silicon oxide, silicon carbide,polysilicon, amorphous silicon, titanium dioxide, and titanium IIIoxide.

According to another aspect of the disclosure a neurological lead caninclude a planar formed, cylindrical film defining a lumen. The planarformed, cylindrical film can include a distal end and a proximal end.The planar formed, cylindrical film may also include a plurality ofelectrodes disposed on an outer surface of the formed cylinder and aribbon cable extending from the distal end of the planar formed,cylindrical film. The ribbon cable can extend into the lumen toward theproximal end of the planar formed, cylindrical film. The lumen of theplanar formed, cylindrical film can be filled with an encapsulatingpolymer, and a tube body can be coupled with the proximal end of theplanar formed, cylindrical film.

The lead can also include a plurality of contact pads disposed on theribbon cable. Each of the plurality of contact pads can be electricallycoupled to at least one of the plurality of electrodes. The lead canalso include a gold layer disposed on each of the plurality of contactpads. The gold layer can be between about 5 μm and about 50 μm thick.The lead can also include a peripheral trace partially surrounding eachof the plurality of electrodes and coupled with each of the plurality ofelectrodes at two or more locations.

In some implementations, the lead can include one or more orientationmarks that are aligned with a directional electrode or the ribbon cable.The one or more orientation marks can be radiopaque.

In some implementations, the at least one of the plurality of electrodesincludes a mesh configuration. One of the plurality of electrodes caninclude rounded corners.

According to another aspect of the disclosure, a method of manufacturinga neurological lead can include providing a planar film comprising adistal end, a proximal end, a plurality of electrodes, and a ribboncable extending from the distal end of the planar film. The method caninclude forming the planar film into a cylinder that defines a lumen.The ribbon cable can be extended into the lumen defined by the cylinder,and then the lumen is filled with an encapsulating polymer.

The method can also include heating the planar film. In someimplementations, the proximal end of the planar film is coupled with acatheter. The ribbon cable can be coupled with the stylet in someimplementations. The method can also include disposing a radiopaque dyeon the planar film.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures described herein are for illustration purposes. In someinstances various aspects of the described implementations may be shownexaggerated or enlarged to facilitate an understanding of the describedimplementations. In the drawings, like reference characters generallyrefer to like features, functionally similar and/or structurally similarelements throughout the various drawings. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the teachings. The drawings are not intended to limitthe scope of the present teachings. The systems and methods may bebetter understood from the following illustrative description withreference to the following drawings in which:

FIG. 1 illustrates an example system for performing neurostimulation.

FIG. 2 illustrates an example stimulation lead for use inneurostimulation.

FIGS. 3A and 3B illustrate the distal end and example stimulation leadin greater detail.

FIG. 4 illustrates a flow chart of an example method for manufacturing astimulation lead.

FIGS. 5A-5M illustrate an example method for manufacturing the MEMSfilm.

FIGS. 6A-6B illustrate the MEMS film being molded into a cylinder.

FIG. 7A illustrates the formed MEMS film coupled to a stylet.

FIG. 7B illustrates the lead wires coupling with the ribbon cable of theMEMS film.

FIG. 7C illustrates the process of wire bonding the lead wire to acontact pad.

FIGS. 8A and 8B illustrates the extension of the ribbon cable into thelumen of the molded MEMS film.

FIGS. 9A and 9B illustrate the proximal end of the stimulation lead.

FIGS. 10A-10C illustrate the placement of the orientation mark along aportion of the body.

FIGS. 11A-11I illustrate MEMS film configurations that include differentelectrode designs.

FIG. 12 illustrates an electrode with redundant periphery traces.

FIGS. 13A and 13B illustrate the application of a second polymeric layerto the first isolating layer illustrated in FIG. 12 .

FIGS. 14A and 14B illustrate equipotential surfaces in an electrode whena voltage is applied at trace boundaries.

FIGS. 15A and 15B illustrate electrode current densities.

FIGS. 16A and 16B illustrate rounded corner electrodes with peripherytraces.

FIG. 17 illustrates a current density distribution in an electrode withrounded corners and coupled to a periphery trace.

FIG. 18 illustrates a MEMS film with a plurality of electrodesconfigured as mesh electrodes.

FIG. 19 illustrates a mesh configured electrode.

FIG. 20 illustrates a mesh electrode configuration with a plurality ofbands.

FIG. 21 illustrates a finite element analysis model of the currentdensity around a mesh gradient electrode.

FIG. 22 illustrates the current density along an arc lengthcircumferential to the electrode modelled in FIG. 21 .

FIG. 23A illustrates a MEMS film with gradient electrodes turnedperpendicular to the length of the stimulation lead.

FIGS. 23B-23E illustrate a finite element analysis of a gradient meshelectrode.

FIGS. 24A and 24B illustrate a MEMS film configuration without a ribboncable.

FIGS. 25A-25C illustrate a MEMS film without a ribbon cable coupled to astyle and coupled with a lead body.

FIGS. 26A-26H illustrate methods for maintaining the cylindrical shapeof the planar formed, cylindrical MEMS film.

FIGS. 27A-27C illustrate example end cap electrodes.

FIG. 28A illustrates a MEMS film coupled to an existing stimulationlead.

FIG. 28B illustrates the MEMS film of FIG. 28A in a planarconfiguration.

FIGS. 29A-29D illustrate the distal end of a stimulation lead configuredwith electrodes distributed longitudinally along the axis of thestimulation lead.

FIGS. 29E and 29F illustrate the MEMS film in a planar configurationbefore being disposed on the external tube.

FIGS. 30A and 30B illustrate the stimulation lead implanted near apatient's spinal cord.

FIG. 31 illustrates the process of electro-galvanically thickeningelectrodes.

FIG. 32A illustrates a cross section of a stimulation lead with noplatinum growth.

FIG. 32B illustrates a cross section of a stimulation lead with platinumgrowth.

FIGS. 33A-33N illustrate the method of manufacturing a MEMS film with asecond, encapsulated metal layer.

FIGS. 34A-34E illustrate an example of a MEMS film with two metallayers.

FIGS. 35A and 35B illustrate an example proximal end of the stimulationlead.

FIG. 36 illustrates an example MEMS film to be disposed within anencapsulating tube.

FIGS. 37A and 37B illustrate two views of a platinum contact.

FIGS. 38A and 38B illustrate the coupling of the contacts with the MEMSfilm.

FIG. 38C illustrates the coupling of lead wires to the MEMS film withcontacts.

FIG. 38D illustrates an example stimulation lead with a MEMS filmdisposed within an encapsulating tube.

DETAILED DESCRIPTION

The various concepts introduced above and discussed in greater detailbelow may be implemented in any of numerous ways, as the describedconcepts are not limited to any particular manner of implementation.Examples of specific implementations and applications are providedprimarily for illustrative purposes.

FIG. 1 illustrates an example system 50 for performing neurostimulation.The system 50 includes a stimulation lead 100 implanted into the brain124 of a patient 102. The stimulation lead 100 is coupled with astimulator 122 through cables 126. The stimulator 122 generatestherapeutic, electrical stimulations that can be delivered to thepatient's brain 124 by the stimulation lead 100.

FIG. 2 illustrates an example stimulation lead 100. The stimulation lead100 includes a body 150. The body 150 may also be referred to as a tubebody, tube, or catheter. The body 150 includes a number of orientationmarks 156. At a distal end 105, the stimulation lead 100 includes a MEMSfilm 110. At a proximal end 180, the stimulation lead 100 includes aplurality of contacts 190.

At the proximal end 180 of the stimulation lead 100, the stimulationlead 100 includes one or more contacts 190. The contacts 190 can be usedto establish an electrical connection between the electrodes of the MEMSfilm 110 and the implanted stimulator 122. For example, each of thecontacts 190 can be coupled with one or more electrodes of the MEMS film110. The stimulator 122 may then couple with the contacts 190 through aplurality of cables 126 to stimulate tissue or record physiologicalsignals.

The distal end 105 of the stimulation lead 100 can include a MEMS film110. FIG. 3A illustrates the distal end 105 and example MEMS film 110 ingreater detail. The MEMS film 110 can be wrapped or assembled around thedistal end 105 of the body 150 or formed into a semi-rigid cylinder thatis coupled to the end of the body 150. The MEMS film 110 includes aplurality of electrodes 120. The MEMS film 110 can also include a ribboncable 125 that wraps over the most distal end of the MEMS film 110 andextends into a lumen defined by the MEMS film 110. As described below,the ribbon cable 125 is coupled with one or more lead wires 160. Aportion of the length of the lead wires 160 are wrapped around a stylet153.

The MEMS film 110 can include one or more electrodes 120. Asillustrated, the MEMS film 110 includes 12 electrodes. In someimplementations, the MEMS film 110 can include between about 6 and about64 electrodes, between about 8 and about 32, between about 8 and about24, or between about 8 and about 12 electrodes. The electrodes 120 canbe configured as directional or omnidirectional electrodes.Omnidirectional electrodes may wrap substantially around (e.g., at least80%, or at least 90%) the circumference MEMS film 110 when the MEMS film110 is formed into a cylinder, and the directional electrodes may wraponly around a portion of the circumference (e.g., less than 80%) theplanar formed, cylindrical MEMS film 110. One or more directionalelectrodes can electrically couple to form an omnidirectional electrode.For example, the three distal most electrodes 120 may be electricallycoupled together to form an omnidirectional electrode at the tip of thestimulation lead 100. In some implementations, the MEMS film 110 caninclude a plurality of omnidirectional electrodes and a plurality ofdirectional electrodes. For example, the electrodes 120 may beconfigured as two omnidirectional electrodes and six directionalelectrodes.

Electrical traces can couple each of the electrodes 120 with one or moreof the lead wires 160. For example, the traces may run under aninsulative layer of the MEMS film 110 to the ribbon cable 125, where thetraces terminate and are coupled with the one or more lead wires 160. Insome implementations, the stimulation lead 100 includes one lead wire160 for each of the electrodes 120. In other implementations, thestimulation lead 100 includes fewer lead wires 160 than electrodes 120because one or more of the lead wires 160 are electrically coupled withmore than one of the electrodes 120. For example, when the MEMS film 110includes two omnidirectional electrodes and six directional electrodes,the stimulation lead 100 may include eight lead wires 160. The leadwires 160 can run along the length of the body 150 toward the proximalend 180 of the body 150. The lead wires 160 may traverse the length ofthe body 150 in the lumen of the body 150. At the proximal end 180 ofthe MEMS film 110, the lead wires 160 may be electrically coupled withthe contacts 190.

FIG. 3B illustrates the underside of the distal end 105 of thestimulation lead 100. In some implementations, the MEMS film 110 can beinitially formed as a planar film that is formed into a cylinder. Thismethod of forming the MEMS film 110 can create a connecting seam 111.

The MEMS film can include a plurality of layers. In someimplementations, the MEMS film includes five layers. The five layers caninclude a first polymeric layer and a first silicon based barrier layerthat is at least partially deposited (or otherwise disposed) over thefirst polymeric layer. The MEMS film 110 can also include a first metallayer that is at least partially deposited (or otherwise disposed) overthe first silicon based barrier layer. Other layers can include a secondsilicon based barrier layer at least partially deposited (or otherwisedisposed) over the first metal layer and the first silicon based barrierlayer. The second silicon based barrier layer can define a firstplurality of through-holes over portions of the first metal layer.Another layer of the MEMS film 110 can be a second polymeric layer thatis at least partially deposited (or otherwise disposed) over the secondsilicon based barrier layer. The second polymeric layer can also definea plurality of through holes. The plurality of through-holes of thesecond silicon based barrier layer and the second polymeric layer aresubstantially aligned to define each of the plurality of electrodes 120and contact pads 145 of the MEMS film 110.

FIG. 4 illustrates a flow chart of an example method 400 formanufacturing a stimulation lead. The method 400 can include forming aplanar MEMS film (step 401). The planar MEMS film can then be moldedinto a cylinder (step 402). A ribbon cable of the MEMS film may then beextended into a lumen of the molded cylinder (step 403). The molded MEMSfilm may then be coupled with a lead body (step 404).

As set forth above, the method 400 can begin with the forming of aplanar MEMS film (step 401). The planar MEMS film may be a planarversion of the MEMS film 110. The planar MEMS film can be referred togenerically as the MEMS film 110. In some implementations, the MEMS film110 includes a plurality of layers. The MEMS film 110 can include one ormore polymeric layers, one or more silicon based barrier layers, and oneor more metal layers. For example, the MEMS film 110 can include a firstpolymeric layer, a first silicon based barrier layer, a first metallayer, a second silicon based barrier layer, a second polymeric layer,and a second metal layer. The silicon based barrier layers can improveadhesion of the layers, improve scratch resistance of the metal layers,and impede the flow of ions and humidity between the layers. Ions andhumidity can traverse a polymeric layer and cause electrical shortcircuits in the metal layer of a MEMS device. The silicon based barrierlayers can prevent or reduce the flow of ions and the introduction ofhumidity into or between the layers. Accordingly, the reduction of ionflow and humidity between the layers by the silicon based barrier layerscan improve the performance and durability of the MEMS film 110.

FIGS. 5A-5M illustrate an example method for manufacturing the MEMS film110. More particularly, FIGS. 5A-5M illustrate a cross-sectional view ofan example thin-film micro-fabrication method for fabricating the MEMSfilm 110. The MEMS film 110 can be fabricated using a plurality oftechniques and the below describe method illustrates one possible methodfor fabricating the MEMS film 110. The fabrication procedure can includea series of procedural steps in which various layers are deposited orremoved (e.g., etched) to achieve a final form. The cross sections inFIG. 5A through FIG. 5M demonstrate the process steps to build a MEMSfilm 110.

In a first step illustrated in FIG. 5A, a carrier substrate 201 isprovided, such as a wafer composed of a crystalline material, such assilicon, or an amorphous material, such as a thermal shock resistantborosilicate glass or other suitable smooth supportive material. A firstlayer 202, which can include one or more sub-layers, is applied to asurface of the wafer 201. One of the sub-layers can be a sacrificiallayer deposited on the wafer 201, which is removed in a subsequentelectrochemical etching step. In some implementations, the sacrificialsub-layer is preceded by another sub-layer, referred to as anunderlayer, which can serve to form the electrochemical cell required toetch the sacrificial layer. The sacrificial sub-layer can be aluminum,or an alloy of aluminum such as AlSi, which has a smaller granularity,whereas the underlayer can be a TiW alloy such as Chrome or similarmetal. In some implementations, when the sacrificial sub-layer is notimplemented, the removal of the resulting device from the substrate isdifficult and could result in damage to the finished device.

Referring to FIG. 5B, the next step in the fabrication process caninclude depositing a first polymeric layer 205. The first polymericlayer 205 can be deposited upon the sacrificial layer 202 by MEMSprocesses such as, but not limited to, (i) spin coating a liquid polymerprecursor such as Polyimide or Silicone precursor; (ii) depositing apolymer through chemical vapor deposition as is done with parylene-C; or(iii) laminating a polymer sheet onto the wafer. In some embodiments,the polymer layer 205 is heated, or baked, to polymerize. In someimplementations, the first polymeric layer 205 includes polyamic-aciddissolved in NMP and spun onto the sacrificial layer 202 in liquid form.The polymeric layer 205 is heated into a imidized polyimide. The polymerin its cured form is between about 5 μm and about 15 μm thick. Thepolymer layers of the MEMS film can serve as a barrier to water,humidity, and isolate the components of the MEMS film.

FIG. 5C illustrates the deposition of a silicon based barrier layer. Thesilicon based barrier layer can serve both as a layer to aid theadhesion and durability of subsequent layers. The silicon based barrierlayer can also serve as an ionic barrier, and limit ions from reachingthe metal layers, which could compromise electrical performance. Thesilicon based barrier layer can also block humidity from reaching theinterlayers and the metal layer, which could create short circuits andcompromise electrical isolation.

In some implementations, the silicon based barrier layer is depositedonto the first polymeric layer 205 by vapor deposition techniques suchas chemical vapor deposition (CV) and plasma enhanced chemical vapordeposition (PECVD), or by sputtering techniques such as direct current(DC) or RF (Radio Frequency) sputtering. The silicon based barrier layercan include Silicon Nitride, Silicon Oxide, Silicon Carbide,Poly-Silicon, or Amorphous-Silicon. The silicon based barrier layer canalso include other non-conductive materials, such as Titanium Dioxide orTitanium (III) Oxide. The final thickness of the silicon based barrierlayer can range from about 20 nm to about 2 μm. In some implementations,the silicon based barrier layer is about 400 nm to about 600 nm, whichcan permit the silicon based barrier layer to be flexible enough to bendduring subsequent assembly techniques.

Now referring to FIG. 5D, a metal layer 215 can be deposited over theentire wafer on the surface of the silicon based barrier layer 210.Subsequently, a photoresist layer 217 can be deposited. The photoresistlayer 217 can be defined by exposing areas of the photoresist layer 217to ultra-violet light and developing those areas in a solvent. Thus, theexposed areas of the photoresist layer 217 will be selectively removedand areas of the metal layer 215 will be exposed. The areas of the metallayer 215 covered by the photoresist layer 217 can form the electrodes,traces, and other components of the final product that are within themetal layer.

The metal layer 215 can include a variety of metals such as titanium,platinum, gold, and others metals used in neuromodulation. To improveadhesion of a metal layer 215, the metal layer 215 can be applied inlayers. For example, the metal layer 215 can be applied as a firstlayer, such as titanium, then a middle layer, such as platinum, andfinally an upper layer, such as titanium. This tri-layer metal structurecan improve adhesion below and above the platinum layer by using thetitanium as an adhesion layer to the silicon based barrier layer. Thetypical thicknesses for the adhesion layer of titanium can be betweenabout 20 nm and about 100 nm or between about 25 nm and about 75 nm.Typical thicknesses for the platinum layer can be between about 200 nmand about 7 μm, between about 400 nm and about 5 μm, between about 400nm about 3 μm, between about 400 nm and about 1 μm, or between about 400nm and about 700 nm. In some implementations platinum can be replaced byanother, high charge transfer capable material such as iridium oxide.

FIG. 5E illustrates the process after the etching of the metal layer215. As illustrated, the metal layer 215 can be locally removed in theareas that were not covered by the photoresist 217. In someimplementations, etching of the metal layer is performed in a plasmaetcher such as a Reactive Ion Etcher. In some implementations, titaniumand platinum can be etched with chlorine gas. After the etching processis finished, the photoresist layer 217 can be removed using a solvent.

Another method to deposit and define the metal layer is using theso-called “lift off” technique. In this method the photoresist layer canbe deposited onto the silicon based barrier layer 210 first. Thephotoresist layer can be defined using photolithography. The metal layer215 can then be deposited through this “lift off” mask, and theremaining photoresist removed in a solvent. In this method the metallayer is transferred onto the silicon based barrier layer without theneed of plasma etching and may have some process costs and speedadvantages.

Referring next to FIG. 5F, a deposition of a second barrier layer 220 isperformed. The second barrier layer can be deposited using the sametechniques as the first silicon based barrier layer 210. The secondbarrier layer 220 can be the same thickness, or a different thickness asthe first silicon based barrier layer. In some implementations, thesecond silicon based barrier layer is optional. The second silicon basedbarrier layer 220 and the first silicon based barrier layer 210 cansubstantially surround (e.g., at least 80%) the metal layer 215,rendering it electrically isolated. In order to etch and define thefirst and second silicon based barrier layer 210 and 220, respectively,a second photoresist layer 227 is deposited and photolithographicallydefined with clean room techniques.

The two silicon based barrier layers are etched, as illustrated in FIG.5G. The silicon based barrier layers can be etched using a plasma etch.An example of an etching process would be a reactive ion etching using atetrafluoromethane gas, (CF4). The second photoresist layer 227 can beremoved using a solvent dissolution.

FIG. 5G illustrates an example where the edges of the silicon basedbarrier layers 210 and 220 are defined, but the etch does not reach themetal layer 215. In some implementations the photolithography caninclude an opening above the metal layer 215, which would result inexposing the metal layer 215.

FIG. 5H illustrates the application of a second polymer layer 230. Thesecond polymer layer 230 can be the same or a different polymer from thefirst polymer layer 205, and it can be the same or a differentthickness.

FIG. 5I illustrates the deposition of a third photoresist 237, which canform the etching perimeter of the first and second polyimide layers 205and 230, respectively. In some implementations, prior to the applyingthe third photoresist 237, a sacrificial layer, such as Silicon Dioxideor Silicon Nitride, is deposited in order to serve as an etch mask forthe polyimide etch. For example, a silicon dioxide layer of thickness ofabout 500 nm can be deposited, which will serve as the etch mask for theprocess.

FIG. 5J illustrates the result of an oxygen plasma etching of the firstand second polyimide layers 205 and 230, respectively. If applied, thesilicon dioxide layer can be removed through an additional etch.

FIG. 5K illustrates the deposition of a fourth photoresist layer 247. Insome implementations, the fourth photoresist layer 247 does not coverpart of the metal layer 215. For example, the opening 232 can bemaintained to create a region for a gold layer to grow.

FIG. 5L illustrates the galvanic growth of a thick gold layer 250 intothe opening 232. In some implementations, the gold layer 250 is achievedby connecting the metal traces in the wafer to a perimetric metal bandthat allows an electrical connection between the edge of the wafer andthe metal opening 232. When immersed in a galvanic bath and a currentapplied, the gold will grow on the metal layer 215 using the metal layer215 as the seed layer for galvanic growth. In some implementations, thegold layer 250 is about 2 μm to about 20 μm thick. The fourthphotoresist layer 247 can be removed using a solvent.

FIG. 5M illustrates the removal of the MEMS film from the wafer 201. Theremoval of the fourth photoresist layer 247 exposes the electrodeopening 233. The MEMS film can be removed from the wafer 201 by theremoval of the sacrificial layer 202 using electrochemically etching.Removal of the sacrificial layer 202 frees the underside of the MEMSfilm from the wafer 201. In some implementations, the sacrificial layer202 is removed by placing the wafer in a saline bath with a high NaClconcentration. A platinum electrode also placed in the bath can be usedas a reference, and a voltage can be applied to the aluminum layer withrespect to the platinum electrode. The electrochemical cell created bythe aluminum and TiW etches the aluminum—separating the MEMS film fromthe wafer 201.

In some implementations, when the MEMS wafer is completed, and theindividual devices have been removed, further process steps can occurbefore to assemble the wafers into a cylindrical shape.

Referring again to FIG. 4 , the method 400 can also include molding theMEMS film 110. In some implementations, the MEMS film 110 is molded intoa cylinder shape that defines a lumen. FIGS. 6A-6B illustrate the MEMSfilm 110 being molded into a cylinder.

FIG. 6A illustrates a planar view of the MEMS Film 110. As illustrated,the MEMS film 110 includes twelve electrodes 120. The electrodes 120 canbe generally rectangular in shape with rounded corners. The ribbon cable125 extends from the distal end of the MEMS film 110. The ribbon cable125 can include one or more traces that electrically couple theelectrodes 120 to the contact pads 145. In some implementations, each ofthe contact pads 145 are electrically coupled with one or moreelectrodes 120.

FIG. 6B illustrates the molded MEMS film 110. In some implementations,the MEMS film 110 is heated to and then molded to form a cylinder. TheMEMS film 110 can be heated and molded using a thermal reflow method. Insome implementations, the MEMS film 110 is heated to about 300° C. whenmolded. The formed cylinder can have an internal diameter of betweenabout 0.5 mm and about 2 mm, between about 1 mm and about 1.5 mm, orbetween about 1.3 mm and about 1.5 mm after formed into a cylinder. Thecylinder shape of the MEMS film 110 can be formed by inserting the MEMSfilm 110 into a tube with the same diameter that is required for thefinal device. The MEMS film 110, within the tube, can be heated to atemperature which causes the polymer insulator to slightly reflow andtake the new form of the tube.

The end of the ribbon cable 125 can be coupled to a stylet 153. FIG. 7Aillustrates the formed MEMS film 110 coupled to the stylet 153. Couplingthe MEMS film 110 to the stylet 153 can render the distal end of theribbon cable 125 rigid and can simplify later assembly steps. Forexample, coupling the stylet 153 with the ribbon cable 125 can ease thecoupling of the lead wires 160 to the contact pads 145. The stylet 153can include a metallic material (e.g., stainless steel), a ceramicmaterial, or a polymeric material. In some embodiments, the stylet 153can be radio-opaque such that the surgeon can visualize the stimulationlead 100 in an x-ray or CT scan during the implantation process tocontrol the final placement of the stimulation lead 100. The stylet 153can also be used to determine the rotation of the stimulation leadbecause the stylet 153 is partly planar along its longitudinal axis.

FIG. 7B illustrates the lead wires 160 coupling with the ribbon cable125 of the MEMS film 110. In some implementations, the lead wires 160are coiled around the stylet 153. The lead wires 160 can be coupled withthe contact pads 145 through laser welding, ultrasonic bonding,crimping, thermocompression bonding, or wire bonding. In someimplementations, the lead wires 160 are locally flattened to increasethe surface area of the lead wires 160 that comes into contact with thecontact pads 145.

FIG. 7C illustrates the process of wire bonding a lead wire 160 to acontact pad 145. As illustrated, a lead wire 160 lies across the contactpad 145. The insulation at the end of the lead wire 160 can be removedso the conductor within the lead wire 160 can make contact with thecontact pad 145. A wire bond 147 connects the contact pad 145 to thelead wire 160. A weld can be formed between the wire bond 147, thecontact pad 145, and the lead wire 160 through the use of heat,pressure, ultrasonic energy, or combinations thereof.

Referring again to FIG. 4 , the method 400 can also include extendingthe ribbon cable into the lumen formed by the molding of the MEMS film(step 403). The ribbon cable 125 can be folded such that a portion ofthe ribbon cable 125 and a portion of the stylet 153 are disposed withinthe lumen defined by the formed MEMS film 110. In some implementations,the lumen defined by the MEMS film 110 can be back filled with anencapsulating polymer, such as an epoxy. The MEMS film 110 can be placedin a cylindrical mold prior to the backfilling with the polymer.Backfilling the MEMS film 110 can serve to secure the lead wires 160 inplace and electrically encapsulate the connections within the lumen. Insome implementations, the backfilling process can also be used to form acylindrical form to the distal end of the stimulation lead 100.

FIG. 8A illustrates the extension of the ribbon cable into the lumen ofthe molded MEMS film 110. The ribbon cable 125 can be folded such that aportion of the ribbon cable 125 and a portion of the stylet 153 isdisposed within the lumen formed by the molded MEMS film 110. Theportion of the ribbon cable 125 and the stylet 153 can be extended intothe lumen by temporarily opening the cylinder along the seam 111.

FIG. 8B illustrates the MEMS film 110 after the backfilling process. Thelumen defined by the MEMS film 110 can be backfilled, or co-molded, witha polymeric material. The backfilling process can seal the MEMS film 110in place and electrically isolate the lead wires 160 connected to thecontact pads 145 at the end of the ribbon cable 125. The backfilledpolymer can fill the interior of the lumen and can also create a distal,hemispherical tip 151. In some implementations, an internal cylinder 161is added proximal to the backfilling material over the lead wires 160.The internal cylinder 161 can reduce abrupt changes in compliance (e.g.,flexibility) in the final device, when transitioning from the flexiblelead wires 160 to the relatively rigid polymeric filling of the backfilled MEMS film 110.

Referring again to FIG. 4 among others, the method 400 can also includecoupling the molded film to a lead body (step 404). The body 150 cancouple with the molded MEMS film 110 by glue or adhesive. In someimplementations, the body 150 can be molded over a portion of theproximal end of the MEMS film 110. In addition to securing the body 150to the MEMS film 110, molding the body 150 over the MEMS film 110 canhelp the MEMS film 110 maintain a cylindrical shape. The proximal end ofthe body 150 can include the one or more contacts 190.

FIGS. 9A and 9B illustrate the proximal end 180 of the stimulation lead100. The proximal end 180 of the stimulation lead 100 can include aplurality of contacts 190. As illustrate, the proximal end 180 of thestimulation lead 100 includes eight contacts 190. Each of the contacts190 are electrically coupled with at least one of the lead wires 160. Insome implementations, the proximal end 180 of the stimulation lead 100is stiffer when compared to other portions of the stimulation lead 100.The added stiffness of the proximal end 180 can assist in the couplingof the proximal end 180 with a stimulator or an extension cable. Thestimulation lead 100 can also include a lumen 182, which is illustratedin FIG. 9B. In some implementations, the lumen 182 runs the length ofthe stimulation lead 100.

FIGS. 10A-10C illustrate the placement of the orientation mark 156 alonga portion of the body 150. The orientation mark 156 can enable aneurosurgeon to determine the placement and rotation of the stimulationlead 100 when the stimulation lead 100 is implanted within the patient.For example, the orientation mark 156 may enable the neurosurgeon todetermine the axial orientation (e.g., rotation) of the stimulation lead100 and determine towards what anatomical structure the directionalelectrodes are facing. In some implementations, the orientation mark 156can be a solid line extending the length of the stimulation lead 100.The orientation mark 156 can also include a dashed line or a series ofdots.

The orientation mark 156 can be aligned with a specific feature (orlandmark of the stimulation lead 100). For example, the orientation mark156 can be aligned with a directional electrode 120, as illustrated inFIG. 10A. In another example, the orientation mark 156 can be alignedwith the seam 111 of the MEMS film 110, as illustrated in FIG. 10B. Theorientation mark 156 can also be aligned with a gap between twoelectrodes 120 or with the ribbon cable 125 (as illustrated, forexample, in FIG. 10C).

The orientation mark 156 can be a stamped ink line or can be applied tothe stimulation lead 100 during the extrusion body 150 as a dye, forexample. The orientation mark 156 can alter the reflectivity of the body150 and may be implemented as a radiopaque ink or dye in order toprovide intra-operative and post-operative imaging. In some embodiments,laser marking can be used to locally change the texture, color, orreflectivity of the body 150 to serve as the orientation mark 156.

The MEMS film 110 can include a combination of stimulating electrodesand recording electrodes. In some implementations, an electrode 120 canbe recording electrode or a stimulating electrode, or both. For example,to act as a stimulating electrode, the electrode 120 may be coupled witha stimulator, and to act as a recording electrode, the electrode 120 maybe coupled with an analog-to-digital converter and an amplifier. In someimplementations, the recording electrodes and the stimulating electrodesmay be shaped or configured differently. For example, the recordingelectrodes may be smaller in size compared to the stimulatingelectrodes.

A neurosurgeon may record from one or more of the electrodes 120 duringthe implantation of the stimulation lead 100. For example, theneurosurgeon may record neurophysiological activity in the beta band(approximately 15-30 Hz) of neural activity because the beta band isclosely associated with motor behavior.

FIGS. 11A-11I illustrate planar MEMS film 110 configurations thatinclude different electrode designs. Each of the MEMS film 110 includethree columns of electrode 120 and can therefore record electricalactivity in three directions, labeled 0 degrees, 120 degrees, and 240degrees. The MEMS film 110 may also include more than three columns ofelectrodes 120 to enable the stimulation lead 100 to record andstimulation in more than three directions. Each of the electrodes 120 ofeach of the different MEMS films 110 can be electrically isolated fromone another to form directional electrodes or one or more of theelectrodes 120 can be electrically coupled to one another to formomni-directional electrodes. For reference, when the MEMS filmsillustrated in FIGS. 11A-11I are molded into a cylinder, the end of theMEMS film toward the bottom of the page is coupled to the body 150.

FIG. 11A illustrates the MEMS film 110 configured to have both elongatedelectrodes 120 and circular electrodes 120. The elongated electrodes caninclude semicircular ends. In some implementations, the circularelectrode may be configured for use as recording electrodes and theelongated electrodes may be configured for stimulating neurologicaltissue. The recording electrodes can record neurological activity duringthe surgical descent of the stimulation lead 100 into the brain. Byhaving recording electrodes close to the stimulation electrode, theelectrical activity captured by the recording electrodes afterstimulation from the stimulating electrodes can be clinically relevantto the stimulation lead 100 placement. In some implementations,recording data captured from any or all recording electrodes can beclinically relevant to determine which of the stimulating electrodesshould be used to stimulate a specific target. FIG. 11B illustrates asimilar implementation, but with electrodes that include rounded cornersrather than semicircular ends.

FIG. 11C illustrates an implementation of a planar MEMS film where theelectrodes 120 are of the same dimensions. In some implementations, themost proximal row of electrodes and most distal rows of electrodes areeach electrically interconnected, and therefore each row can act as acircumferential electrode.

FIG. 11D illustrates a planar MEMS film with electrodes 120 configuredas circular electrodes. The electrodes 120 configured as circularelectrodes may improve charge density considerations around the edges ofthe electrode. FIG. 11E illustrates a planar MEMS film with electrodes120 configured as circular electrodes of different sizes. The largercircular electrodes may be used for stimulation and the smaller circularelectrodes may be used for recording. FIG. 11F illustrates a planar MEMSfilm with electrodes 120 configured as circular electrodes where therows are placed closely together.

FIG. 11G illustrates a planar MEMS film with an electrode arrangementwhere the electrodes 120 are configured as elongated electrodes andcircular electrodes. The elongated electrodes can be configured asrecording electrodes and are interlaced along each row with the circularelectrodes, which may be configured as stimulating electrodes. FIG. 11Hillustrates a planar MEMS film with an electrode arrangement where eachelectrode 120 includes an inner portion 294 and an outer portion 292. Insome implementations, the inner portion is a stimulation electrode andthe outer portion 292 is a recording electrode. FIG. 11I illustrates aplanar MEMS film where each electrode includes four bands 299. In someimplementations, two or more of the bands 299 are electrically coupledtogether.

One or more of the electrodes 120 can include redundant traces thatimprove reliability of the stimulation lead 100. The electrodes 120 canbe connected to the contact pads 145 on the end of the ribbon cable 125via metal traces that are embedded in the MEMS film 110. The traces canhave several redundancies around the periphery of the electrode 120 toreduce the likelihood that the electrode 120 will become disconnectedfrom the contact pad 145 to which the electrode 120 is coupled. Thisdesign is demonstrated in FIG. 12 , for example, with a simplifiedembodiment of a MEMS electrode film 300.

FIG. 12 illustrates a MEMS film with electrodes with redundant peripherytraces. As illustrated a metal layer is deposited onto a polymeric layer305. The metal layer can include the contact pads 145, the traces 315,the periphery traces 314, and the electrodes 120. Each periphery trace314 can extend around the perimeter of an associated electrode 120. Theperiphery trace 314 can be coupled with an electrode 120 at a pluralityof connection points 316. Each electrode 120 can include four connectionpoints 316. In some implementations, each electrode 120 includes one ormore connection points 316 per edge of the electrode 120. For example,the electrodes 120 illustrated in FIG. 12 are squares with four edgesand one connection point 316 per edge. In some implementations, thecontact pads 145 can also be surrounded by a periphery trace 314.

FIGS. 13A and 13B illustrate the application of a second polymeric 325(or isolating layer) to the first isolating layer 305 illustrated inFIG. 12 . The second polymeric layer 325 can include a plurality ofthrough holes 310 that align with the electrodes 120 and the contactpads 145. The silicon based barrier layer that can be deposited over themetal layer can also include a plurality of through holes that alignwith the through holes 310 of the second polymeric layer. The secondpolymeric 325 can be bonded to the surface of the first polymeric layer305 and the metal conductive layer. The second polymeric 325 can bephotolithographically defined. The resulting stack of layers isdemonstrated in FIG. 13B, where the electrodes 120 and correspondingcontact pads 145 are apparent through the through holes 310, but thetraces 315 and periphery traces 314 are hidden from view andelectrically isolated from the outside environment.

FIGS. 14A and 14B illustrate equipotential surfaces in an electrode whena voltage is applied at trace boundaries. In FIG. 14A, the electrode isonly coupled to a single trace 315 and does not include a peripherytrace 314. In some implementations, the junction between the trace 315and the electrode 120 is an area where the applied voltage is highest.FIG. 14A illustrates the equipotential surfaces 332 in an electrode 120when a voltage is applied at trace 315. The potential is concentrated ata corner, near the junction between the trace 315 and the electrode 120.In some implementations, the concentrated potential can contribute todevice reliability issues at the junction. FIG. 14B illustrates anelectrode 120 with a peripheral trace 314. The peripheral trace 314,with four connection points to the electrode 120 better distributes thepotential 337 throughout the electrode 120. The distribution of thepotential can increase electrode health and provide redundancies if oneof the connection points break.

The electrodes 120 can include rounded electrode corners to decreasefocal points of current density on each of the electrodes 120. FIG. 15Aillustrates rectangular electrode 120 with a voltage applied to theelectrode. High current densities can be generated at the corners of theelectrode in this example. FIG. 15B illustrates an electrode 120 withrounded or semicircular ends, which can reduce the current densityrelative to rectangular corners. Reducing current density can protectthe electrode from degradation.

FIGS. 16A and 16B illustrate example rounded corner electrodes withperiphery traces. FIG. 16A illustrates a MEMS film with four roundedcorners electrodes 120. The electrodes 120 are connected to contact pads145 through the traces 315. The trace 315 are coupled with peripherytraces 314 that enable voltage distribution to be equal at contactpoints 316, and thereby distributed the voltage more evenly across theelectrode surface. As illustrated, the periphery traces 314 do notencircle the perimeter of the electrodes 120; however, in someimplementations, the periphery traces 314 can fully encircle theperimeter of the electrodes 120. FIG. 16B illustrates the MEMS film witha second polymeric layer 375 in place, encapsulating the peripherytraces 314 and the traces 315.

FIG. 17 illustrates a current density distribution in an electrode withrounded corners and coupled to a periphery trace. A rounded cornerelectrode 120 is fully surrounded by a periphery trace 314. Theperiphery trace 316 makes two connections to the electrode 120. When apotential is applied to the trace 315, the equipotential regions 382distribute around the periphery trace 316 and enter the electrode 120 atthe two connection points. By applying the potential to multiple pointsof the electrode 120, the potential is more evenly distributed acrossthe electrode 120.

The electrodes 120 can include meshes. FIG. 18 illustrates a MEMS film110 with a plurality of electrodes 120 configured as mesh electrodes. Amesh electrode configuration can be used to concentrate current densityin certain areas of the electrode surface—for example, the center. FIG.19 illustrates an electrode 120 configured as a mesh electrode. A meshelectrode 120 can include a plurality of concentric bands. In someimplementations, each of the bands are of the same thickness and inother implementations, as illustrated in FIG. 19 , each of the bands maybe narrower toward the center of the electrode 120. Narrowing each ofthe bands towards the center of the mesh electrode 120 can increasecurrent density towards the center of the electrode 120, and therebylimit the spread of current from the electrode's perimeter. In someimplementations, a mesh electrode has the effect of concentrating thevolume of tissue being influenced by the electric current to the centerof the electrode, therefore increasing the effect of directionalstimulation in the patient.

FIG. 20 illustrates a mesh electrode configuration with a plurality ofbands. The MEMS film 420 includes a plurality of mesh gradientelectrodes 427. Each of the mesh gradient electrodes 427 includes aplurality of electrode bands 423. In some implementations, the bands arenarrower toward the center of the mesh gradient electrode 427. Thenarrowing of the bands can concentrate current density towards thecenter of the electrode 427. FIG. 21 illustrates a finite elementanalysis model of the current density 425 around a mesh gradientelectrode, which shows that current density is the highest toward thecenter of the mesh gradient electrode 423. FIG. 22 illustrates thecurrent density 425 along an arc length circumferential to the electrodemodelled in FIG. 21 . The numerical analysis illustrated in FIGS. 21 and22 shows that current density peaks can be shifted away from theperiphery of the electrodes and into the center of the electrode usingmesh electrodes.

FIG. 23A illustrates a MEMS film with gradient electrodes turnedperpendicular to the length of the stimulation lead 100. The gradientmesh electrode 427 is implemented on the MEMS film to concentrate avolume of the current longitudinally along the MEMS film. FIGS. 23B and23C illustrate a finite element analysis model of the electric potentialat the surface of the gradient mesh electrode 427 when in contact withconductive media. The numerical analysis demonstrates that the currentdensity peaks 426 can be shifted away from the periphery of theelectrodes and toward the center of the electrode 427 using a gradientmesh. FIG. 23D illustrates the peaks of current density 426 along theelectrode longitude, and suggests that with proper gradient meshing thepeaks of high current density can be driven away from the peripherytoward the center of the electrode. FIG. 23E illustrates the differencebetween current density 2301 of a non-meshed electrode. The currentdensity 2301 of the non-meshed electrode includes current density peaksat its periphery. The current density 2302 of the gradient meshelectrode includes a plurality of peaks toward the center of theelectrode.

In some implementations, the gradient mesh configurations increaseefficacy of electrical stimulation in human subjects by avoiding sideeffects and concentrating a stimulation signal on regions of intendedtargets.

FIGS. 24A and 24B illustrate a MEMS film 110 configuration without aribbon cable. FIG. 24A illustrates a MEMS film 110 without a ribboncable in a planar configuration. A contact pad area 525 extends from theMEMS film 110. The contact pad area 525 a plurality of contact pad 145.The electrode 120 is electrically coupled with one or more contact pads145 by traces. The MEMS film 110 can also include a plurality of vias527 (or holes in the MEMS film 110). The vias 527 can aid in assembly,by enabling the encapsulating epoxy to flow around the contact pad area525 and fully encapsulate the contact pad area 525. The vias 527 canalso improve bending at the junction of the MEMS film 110 and thecontact pad area 525.

FIG. 24B illustrates the MEMS Film 110 after thermal reforming into acylindrical shape. The molded MEMS film 110 defines an inner lumen 530.The contact pad area 525 is folded into the lumen 530. In someimplementations, the lumen 530 is backfilled with an encapsulatingepoxy.

FIG. 25A illustrates MEMS film without a ribbon cable coupled to a styleand coupled with a body 150. As illustrated the top portion of the MEMSfilm without a ribbon cable is removed to view the interior of the lumendefined by the molded MEMS film. The contact pad area 525 is coupledwith a stylet 153 and lead wires 160 are coupled with the contact pads145. FIG. 25B illustrates the same embodiment as illustrated in FIG.25A, but from a different angle. In these and other examples, sectionsof the MEMS film are removed to illustrate the inner features.

FIG. 25C illustrates the MEMS Film 110 without a ribbon cable in anassembled and overmolded state. After the lead wires 160 are welded inplace, MEMS Film 110 is back-filled with a polymer or epoxy solution toorder to fortify the cylindrical shape. The polymer also encapsulatesand isolates the lead wires 160 connections to the contact pads 145. Insome implementations, the MEMS film without a ribbon cable is morereliable compared to a MEMS film with a ribbon cable. The contact padarea 525 can also provide more spacing between electrode sites 120 fortraces leading to the contact pads 145.

FIGS. 26A-26H illustrate methods for maintaining the cylindrical shapeof the planar formed, cylindrical MEMS film. FIG. 26A illustrates a MEMSfilm 110 that can maintain the cylindrical shape with hooks and clips.The MEMS film 110 can include two hooks 607 and two notches 605, orother number of hooks or notches. FIG. 26B illustrates the planarformed, cylindrical MEMS film 110 with the hook 607 coupled with thenotch 605. When the MEMS film 110 is formed into a cylinder, the hook607 and notches 605 on opposite sides of the MEMS film 110 are alignedwith one another. Each hook 607 can slide into the recess of itsmatching notch 607. In some implementations, the seam of the planarformed, cylindrical MEMS film 110 may also be glued in place.

FIG. 26C illustrates the use of securing holes 625 to maintain thecylindrical shape of the planar formed, cylindrical MEMS film 110. TheMEMS film 110 includes a hole 625 at each of the corners of the MEMSfilm 110. In some implementations, the MEMS film 110 can also includeaddition holes 625 along each long edge of the MEMS film 110. Asillustrated in FIG. 26D, when the MEMS film 110 is formed into acylinder, two holes 625 are aligned with one another. A wire 627 can berun through each of the holes 625 to secure the seam and maintain thecylindrical shape of the planar formed, cylindrical MEMS film 110. Thewire 627 can be a metal or polymer wire, a staple, or a clip.

FIG. 26E illustrates the distal end of a planar formed, cylindrical MEMSfilm 110. The MEMS film 110 can include an under hang 634 that ispositioned under the opposite edge 632 of the MEMS film 110. The underhang 634 can provide a platform for applying an adhesive. The under hang634 and the opposite edge 632 can be mechanically pressed together toform a seal at the seam of the planar formed, cylindrical MEMS film 110.In some implementations, the under hang 634 can extend into the lumendefined by the planar formed, cylindrical MEMS Film 110. In theseimplementations, when the lumen is backfilled with epoxy, the under hang634 can be trapped within the epoxy, preventing the unravelling of theplanar formed, cylindrical MEMS Film 110. In some implementations, asillustrated in FIG. 26F, the under hang embodiment can include aplurality of holes 625. As in the above, illustrated example, the twoedges of the MEMS film 110 can be bound together by a wire 627 thatpasses through each of the holes 625.

FIGS. 26G and 26H illustrate an over molding method for maintaining thecylindrical shape of the planar formed, cylindrical MEMS film 110. Onceformed into a cylindrical shape, an end cap can form a collar 655 overthe distal end of the MEMS film 110. The body 150 can form a collar 655over the proximal end of the MEMS film 110. As illustrated by FIG. 26H,the collar 655 of the end cap (and the collar 655 of the body 150)overlaps the MEMS film 110 by a predetermined distance 657. In someinstances, the collar 655 may extend longitudinally over the seam 111 inorder to enclose the gap formed by the edges of the MEMS film 110 alongthe length of the cylinder shape.

The stimulation lead 100 can include distal recording sites on the endcap of the stimulation lead 100. FIG. 27A illustrates an example MEMSfilm 110 with end cap electrodes. The stimulation lead 100 can include aplurality of end cap electrodes 715 coupled with the end cap 725 of thestimulation lead 100. As illustrated in FIG. 27A, the stimulation lead100 includes five end cap electrodes 715 disposed along four end tags710. The end cap electrodes 715 can be used to identify neural activityduring the implantation of the stimulation lead 100 into a patient'sbrain. The end tags 710 can be coupled with the end cap to ensure thatthe end cap electrodes 715 remain in in place during implantation.

FIG. 27B illustrates an end view of the stimulation lead 100 configuredto include distal recording sites. As described above, the stimulationlead 100 may include five end cap electrodes 715 disposed on the surfaceof the end cap 725. The stimulation lead 100 may include a central endcap electrode 715 and then a plurality of end cap electrodes 715positioned slightly proximal to the central end cap electrode 715. Insome implementations, one of the end cap electrodes 715 positionedslightly proximal to the central end cap electrode 715 is pointed ineach of the anterior, posterior, lateral, and medial directions.

FIG. 27C illustrates the planar MEMS film 110 with end cap electrodes715. Four end tags 710 extend from the distal end of the MEMS film 110.In some implementations, the MEMS film 110 may include more than fourend tags 710. For example, the MEMS film 110 may include between 5 and12 end tags 710. At least one end cap electrode 715 is disposed on eachof the end tags 710. In some implementations, one of the end tags 710 islonger and includes an additional end cap electrode 715. The longer endtag 710 can extend to the apex of the end cap 725, and the end capelectrode 715 at the end of the loner end tag 710 is the central end capelectrode 715 when applied to the end cap 725.

A MEMS film can couple with an existing stimulation lead. FIG. 28Aillustrates a MEMS film 730 coupled to an existing stimulation lead,such as a Medtronic 3389 DBS Lead (Medtronic Inc., MN). The MEMS film730 can be positioned between or around existing ring electrodes 755.The MEMS film 730 can add additional electrodes 120 and end capelectrodes 715 to the existing stimulation lead. The addition of theMEMS film 730 can add the ability of recording or stimulatingdirectionally to the existing stimulation lead. FIG. 28B illustrates theMEMS film 730 in a planar configuration. The MEMS film 730 includes fourelectrodes 120 disposed along a single arm 742 and one end cap electrode715. In some implementations, the MEMS film 730 includes multiple rowsof electrodes 120 disposed across one or more arms 742. Each of the arms742 can be configured to fit between each of ring electrodes 755.

The stimulation lead can have electrodes distributed longitudinallyalong the axis of the stimulation lead. The electrodes can bedistributed longitudinally along the axis of the stimulation lead toenable for flexion between electrode locations. A flexible stimulationlead can be used in spinal cord or pelvic floor stimulation, forexample.

FIG. 29A illustrates the distal end of a stimulation lead 760 configuredwith electrodes distributed longitudinally along the axis of thestimulation lead 760. The stimulation lead 760 includes a MEMS film 770,which can enable flexion between electrode sites. The MEMS film 770 isconnected to the lead wires 160 which are within the external tube 765to which the MEMS film 770 is disposed.

FIGS. 29B-29D illustrates enlarged views of the distal end of thestimulation lead 760. The MEMS film 770 includes a plurality ofelectrodes 120 that wrap around the circumference of the external tube765. Each electrode 120 is coupled with a contact pad 145 through tracesembedded in a respective ribbon cable 125. A lead wire 160 is connectedand bonded to each of the contact pads 145 through welding, bonding, orgluing to electrically coupled each of the electrodes 120 to theproximal end of the MEMS film 770. All subsequent electrode sites 775 onMEMS film 770 are assembled in the same manner. FIG. 29C and FIG. 29Dprovide additional planar perspectives of the same distal end of theNeurostimulation lead 760.

FIG. 29E illustrates the MEMS film 770 in a planar configuration beforebeing disposed on the external tube 765. The MEMS film 770 includes aplurality of electrodes 120 disposed on tabs 780. The tabs 780 areconnected together by the ribbon cable 125, which includes the contactpad 145 for at least one of the electrodes 120. FIG. 29F illustratesanother configuration of the MEMS film 770 where more than one electrode120 is disposed on each of the tabs 780. The number of contact pads 145is increased on each ribbon cable 125 to match the number of electrodes120 disposed on each of the tabs 780. In some implementations, between 2and 12 electrodes can be disposed on each of the tabs 780.

FIGS. 30A and 30B illustrate the stimulation lead 760 implanted near apatient's spinal column. The flexible nature of the stimulation lead 760enables the stimulation lead 760 to be inserted between vertebrae 815 tobe positioned near the spinal cord 817.

In some implementations, the platinum electrodes are thickened. Theplatinum of the electrodes can be electro-galvanically thickened pastits native thickness. For example, one method is to insert the distalend of the stimulation lead into an electro-galvanic bath and applycurrent to the contacts in order to initiate the growth of a platinumlayer. FIG. 31 illustrates the process of electro-galvanicallythickening electrodes. A stimulation lead 100 is inserted into a bath842 and a current is applied using a galvanic source 845. In someimplementations, one advantage of growing the thickened layer on themolded stimulation lead 100, and not the planar stimulation lead 100 onits carrier wafer, is that the thickened layer may not be stressed whensubsequently molded into the cylindrical shape. In theseimplementations, plasma deposition methods may be used to depositadditional platinum, or other materials such as iridium oxide, tothicknesses greater than the native thickness of the electrode.

FIG. 32A illustrates a cross section of a stimulation lead 100 with noplatinum growth, and FIG. 32B illustrates a cross section of astimulation lead 100 with platinum growth. FIGS. 32A and 32B illustratethat each stimulation lead 100 include a first polyimide layer 870, afirst silicon based barrier layer 872, a first metal layer 878, a secondsilicon based barrier layer 874, and a second polyimide layer 876. Asillustrated in FIG. 32B, a galvanically grown platinum layer 880 isdeposited on regions where the metal seed layer 878 is exposed. Thegrowth of a platinum layer 880 can be close to the superior surface ofthe second polyimide layer 876 (e.g., within a few microns), or theplatinum layer 880 can provide a platinum thickness that is flush to thesurface of the second polyimide layer 876.

In some implementations, the traces, or other metal components of thestimulation lead 100 are disposed in a second metal layer below themetal layer that includes the electrodes 120. Traces in a second metallayer enable the traces to connect to the contact pads and electrode asplaces other than the edge of the contact pad or electrode. This canenable a more uniform current density for the contact pads andelectrodes. Also, each connection to the electrode can make contact withthe same electrical potential—improving the uniformness of the currentdensity. FIGS. 33A-33N illustrate the method of manufacturing a MEMSfilm with a second encapsulated metal layer.

FIG. 33A illustrates the first step of the process where a carriersubstrate 901 is provided. A first layer 902 including at least twosub-layers can be applied to a surface of the substrate 901. One of thesub-layers of the first layer 902 can be a sacrificial layer which islater removed in a subsequent electrochemical etch step to separate thefinished MEMS film from the carrier substrate 901. The sacrificialsub-layer can be preceded by another sub-layer, referred to as anunderlayer, which can serve to form the electrochemical cell to etch thesacrificial layer.

Referring to FIG. 33B, the next step in the fabrication process caninclude depositing a first polymeric layer 905 upon the sacrificiallayer 902. The first polymeric layer can be between about 2 μm and about15 μm thick.

Referring to FIG. 33C, a silicon based barrier layer 910 can bedeposited. The silicon based barrier layer 910 can be between about 500nm and about 5 μm thick, which can enable the silicon based barrierlayer 910 to be flexible enough to bend during subsequent assemblytechniques.

FIG. 33D illustrates a first metal layer 915 deposited over the entirewafer on the surface of the silicon based barrier layer 910. Thestructures within the first metal layer 915, such as traces andcontacts, can be structured using photolithographic techniques. Thefirst metal layer 915 can be generally incorporated by depositingseveral metal layers, such as Titanium, Platinum, and again Titanium, toform a tri-layer which can improve adhesion. The tri-layer can bedeposited with thicknesses of 50 nm, 300 nm, and 50 nm respectively.

Referring to FIG. 33E, a second silicon based barrier layer 920 can bedeposited. The second silicon based barrier layer 920 can be depositedusing the same techniques as the first silicon based barrier layer 910and can be generally of a similar thickness. In some implementations,the second silicon based barrier layer 920 is slightly thinner than thefirst silicon based barrier layer 910. As illustrated by FIG. 33E, thesecond silicon based barrier layer 920 and the first silicon basedbarrier layer 910 completely surround the metal layer 915 rendering itelectrically isolated.

FIG. 33F illustrates that a local etching of the second silicon basedbarrier layer 920 can be performed to create creates a silicon basedbarrier layer via (or through hole) 917 that exposes the first metallayer 915.

Referring to FIG. 33G, a second metal layer 925 is deposited on thesurface of the second silicon based barrier layer. The second metallayer 925 includes similar metal to the first metal layer 915, and canbe about the same or similar thickness to the first metal layer 915. Thesecond metal layer 925 comes into electrical contact with the firstmetal layer 915 through the silicon based barrier layer via 917.

FIG. 33H illustrates the depositing of a third silicon based barrierlayer 927. The third silicon based barrier layer 927 can be deposited ina method similar to the first silicon based barrier layer 910, and canbe of the same or similar thickness as the first silicon based barrierlayer 910.

FIG. 33H illustrates the etching of the layers. The silicon basedbarrier layers can be etched using a plasma etch. An example of anetching process includes a reactive ion etching using atetrafluoromethane gas, (CF4). A photoresist layer can be used to definewhich areas are etched. Openings in the third silicon based barrierlayer 927 can be created in order to expose the second or first metallayers.

FIG. 33I illustrates a second polymer layer 930 deposited on thesubstrate. The second polymer layer 930 can be the same or a differentpolymer from the first polymer layer 905, and the second polymer layer930 can be the same or a different thickness. In some implementations,the second polymer layer 930 is polyimide and is between about 2 μm andabout 15 μm thick.

FIG. 33J illustrates the result of an oxygen plasma etching of the firstand second polyimide layers 905 and 930, respectively. The etchingprocess creates openings 932 in the second polyimide layer 930 to exposethe third silicon based barrier layer 927.

FIG. 33K illustrates the etching of the third silicon based barrierlayer 925 to create metal openings 933 to expose the second metal layer925. In some implementations, the openings 933 can also descend toregions of the first metal layer 915. The openings 933 can define theregions of the electrodes 120 that come into contact with the neuraltissue or for define contact pads 145.

FIG. 33L illustrates the deposition of a photoresist layer 935 over thesubstrate. The photoresist layer 935 can maintain the exposed metalopening 933. The opening 937 in the photoresist layer 935 can create aregion for a gold layer to grow.

FIG. 33M illustrates the galvanic growth of a thick gold layer 940 inthe opening 937. The gold layer 940 can be grown by connecting all metaltraces in the wafer to a perimetric metal band that allows electricalconnection between the edge of the wafer and the metal opening 937. Insome implementations, the gold growth layer 940 of about 5 μm to about20 μm thick.

FIG. 33N illustrates that the photoresist layer 935 has been removed toexpose the electrode opening 943. The MEMS film is now removed from thewafer 901 by the removal of the sacrificial layer 902 usingelectrochemically etching.

FIGS. 34A-34E illustrate an example of a MEMS film with two metallayers. FIG. 34A illustrates a first metal layer 915 deposited over afirst polymeric layer and silicon based barrier layer 953. The placementof the traces in a different metal layer than the electrodes can improvethe potential distribution on the surface of electrodes by dispatchingtraces from a central point of equivalent potential. For example, apotential or current can be applied to the pad 959, the current travelsdown the trace 315 toward an equipotential cross 955 at a givenpotential. From the equipotential cross 955, the current travels to eachof the four extremities 954 at similar potentials to one another.

FIG. 34B illustrates the application of the second silicon based barrierlayer 920. The second silicon based barrier layer 920 includes a numberof vias 917 that are configured to align with the ends of theextremities 954 and the pads 959.

FIG. 34C illustrates the application of a second metal layer to thesilicon based barrier layer 920. The second metal layer includes theelectrodes 120 and the contact pads 145. Each of the electrodes 120includes a plurality of contact points 977 that make contact with thefirst metal layer 915 through the vias 917. In other implementations,the electrodes 120 do not include contact points 977, and the electrodes120 make contact with the first metal layer 915 through vias 917 thatare positioned within the body of the electrodes 120.

FIG. 34D illustrates the application of the third silicon based barrierlayer and the second polyimide layer 930. The third silicon basedbarrier layer and the second polyimide layer 930 include through holes982 that define the electrodes 120 and the contact pads 145.

FIG. 34E illustrates the complete MEMS film. The second polyimide layer930 defines the electrodes 120 and the contact pads 145. In someimplementations, the use of a second metal layer improve the permissibleelectrode sizes, orientation, and quantity because moving the traces toa separate layer frees surface area within the electrode metal layer,enabling greater freedom to move and arrange electrodes.

FIG. 35A illustrates an example proximal end 180 of the stimulation lead100. In some implementations, the proximal end contacts 190 can beimplemented as a MEMS film. Implementing the proximal end contacts 190as a MEMS film can decrease the diameter of the proximal end 180 andimprove the manufacturability of the proximal end contacts 190. Theproximal end 180 can be configured to be compatible with existingextension cables such as the Medtronic 37081 cable. The extension cablescan couple the stimulation lead 100 with the implantable stimulator 122,which can be, for example, a Medtronic Activa PC. In someimplementations, the proximal end 180 can be configured to be compatiblewith extension cables that have a smaller pitch between the contactsthan compared to the Medtronic 37081. The MEMS film 1910 of the proximalend 180 can be manufactured using the above described MEMS filmmanufacturing methods. For example, the proximal MEMS film 1910 can beformed as a planar film that is premolded into a cylindrical shape andbackfilled with a polymer or epoxy. FIG. 35B illustrates the proximalend 180 from a different angle.

As illustrate in FIGS. 35A and 35B, the MEMS film 1910 includes a distalportion 1915, which incorporates a plurality of contact pads 145 thatelectrically couple the MEMS film 1910 to the lead wires 160, which runthrough the lead body 150 toward the distal end of the stimulation lead100. A proximal portion 1915 of the MEMS film 1910, can include aplurality of proximal contacts 190. The proximal contacts 190 can be inelectrical communication with one or more of the contact pads 145 on thedistal portion 1915 of the MEMS film 1910. In some implementations, thecontact pads 145 are ring electrodes. The proximal portion 1911 anddistal portion 1915 of the MEMS film 1910 can be coupled with oneanother by one or more interconnects 1925. Traces electrically couplingthe contacts 190 of the proximal portion 1911 with the contacts 145 ofthe distal portion 1915 can be housed within the interconnects 1925. Insome implementations, redundant traces are included within the at leastone of the interconnects 1925. Redundant traces can help guard against adevice failure should one interconnect 1925 break. A lumen 1950 isdefined through the proximal end 180 of the stimulation lead 100. Thelumen 1950 can be configured to permit the passage of an implantationstylet, which can provide stiffness to the stimulation lead 10 duringimplantation.

In some implementations, the proximal end 180 can include a stiff regiondistal to the proximal end contacts 190. The stiff region can be betweenabout 1 cm and about 5 cm or between about 1.5 cm and about 2.5 cm long,e.g., substantially 2 cm. The stiff region can help a neurosurgeon pushthe proximal end 180 into the female end of an extension cable.

In some implementations, the proximal contacts 190 can be thickenedusing the above described electro-galvanic deposition methods.Thickening the proximal contacts 190 can be advantageous for repeatedcoupling of an extension cable to the proximal end 180 because thethickened metal layer can improve the proximal contacts' resistances toscratches, making the proximal contacts 190 more reliable and durable.In some implementations, the MEMS film techniques described herein canalso be used to implement the extension cable.

In some implementations, a MEMS film can be disposed within anencapsulating tube that is coupled with the body 150. FIG. 36illustrates an example MEMS film 110 disposed within an encapsulatingtube. The MEMS film 110 can include a plurality of bond pads 1961 ontowhich contacts can be coupled. In some implementations, the bond pads1961 are metal surfaces similar to the electrodes 120. In someimplementations, the internal MEMS film 110 can have a smaller diameterwhen formed into a cylinder than compared to, for example, the cylinderformed from the MEMS film 110 illustrated in FIG. 3A where the MEMS film110 is not disposed in an encapsulating tube. The diameter of the tubeencapsulated MEMS film 100 can be between about 0.5 mm and about 1.5 mm.The internal MEMS film 110 can also include a plurality of contact pads145.

FIGS. 37A and 37B illustrate two views of a contact 1970. In someimplementations, the contact 1970 can be relatively thicker whencompared to an electrode 120. The contact 1970 can be formed bylongitudinally splitting a platinum cylinder with a lumen into aplurality of sections. In some implementations, the platinum cylindercan have an internal diameter between about 0.5 mm and about 1.5 mm andan external diameter between about 0.7 mm and 1.7 mm. In someimplementations, a wall of the platinum cylinder is about 0.2 mm thick.The platinum cylinder can be divided into contracts 1970 by lasermicromachining the cylinder. In some implementations, the contacts 1970include platinum, titanium, or other conductive materials with aniridium oxide coating.

FIGS. 38A and 38B illustrate the coupling of the contacts 1970 with theMEMS film 1955. As illustrated, a contact 1970 is coupled with each ofthe bond pads 1961. In some implementations, the contacts 1970 arecoupled with the bond pads 1961 by, for example, laser welding,thermocompression bonding, ultrasonic bonding, conductive gluing, wirebonding, or brazing. FIG. 38B illustrates a contact 1970 coupled to eachof the bonding pads 1961. In some implementations, each of the contacts1970 is much thicker than the MEMS film 110. Once coupled with the MEMSfilm 110, the contacts 1970 are electrically coupled to the contacts 145through traces embedded within the MEMS film 110. In someimplementations, the contacts 1970 are coupled with the MEMS film 110after the MEMS film 110 is formed into a cylinder and made rigid by, forexample, backfilling the defined lumen with a polymer. In someimplementations, the bonding pads 1961 are substantially the same sizeas the portion of the contacts 1970 that is coupled with the MEMS film110. In other implementations, the bonding pads 1961 can be larger orsmaller than the portion of the contacts 1970 that are coupled with theMEMS film 10. In some implementations, the contact bonding pads 1961 canbe cylindrical contacts, or include different sizes and geometries, withsome sizes dedicated to simulation, while others are dedicated torecording.

FIG. 38C illustrates the coupling of lead wires 160 to the MEMS film 110with contacts 1970. The lead wires 160 can be coiled as they run thelength of the body 150. A lead wire 160 can be coupled with each of thecontact pads 145. FIG. 38D illustrates an example stimulation lead witha MEMS film disposed within an encapsulating tube. The encapsulatingtube 1990 encapsulates the MEMS film 110, including the contact pads 145and the end of the lead wires 160. When encapsulated in the tube 1990,the contacts 1970 are exposed and can be flush with the outer surface ofthe tube 1990. The tube 1990 can be flush with the body 150. In someimplementations, the tube 1990 is formed by overmolding the MEMS film110 with an epoxy. The overmolding can secure the contracts 1970 to theMEMS film 110 while keeping the surface of the contacts 1970 exposed inorder to conduct electrical current to the target site. The overmoldingcan also electrically isolate the contacts 145 and lead wires 160.

Various implementations of the microelectrode device have been describedherein. These embodiments are giving by way of example and not to limitthe scope of the present disclosure. The various features of theembodiments that have been described may be combined in various ways toproduce numerous additional embodiments. Moreover, while variousmaterials, dimensions, shapes, implantation locations, etc. have beendescribed for use with disclosed embodiments, others besides thosedisclosed may be utilized without exceeding the scope of the disclosure.

Devices described herein as either acute or chronic may be used acutelyor chronically. They may be implanted for such periods, such as during asurgery, and then removed. They may be implanted for extended periods,or indefinitely. Any devices described herein as being chronic may alsobe used acutely.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Modifications and variations can bemade without departing from its spirit and scope of this disclosure.Functionally equivalent methods and apparatuses may exist within thescope of this disclosure. Such modifications and variations are intendedto fall within the scope of the appended claims. The subject matter ofthe present disclosure includes the full scope of equivalents to whichit is entitled. This disclosure is not limited to particular methods,reagents, compounds compositions or biological systems, which can vary.The terminology used herein is for the purpose of describing particularembodiments, and is not intended to be limiting.

With respect to the use of substantially any plural or singular termsherein, the plural can include the singular or the singular can includethe plural as is appropriate to the context or application.

In general, terms used herein, and especially in the appended claims(e.g., bodies of the appended claims) are generally intended as “open”terms (e.g., the term “including” should be interpreted as “includingbut not limited to,” the term “having” should be interpreted as “havingat least,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). Claims directed toward the described subjectmatter may contain usage of the introductory phrases “at least one” and“one or more” to introduce claim recitations. However, the use of suchphrases should not be construed to imply that the introduction of aclaim recitation by the indefinite articles “a” or “an” limits anyparticular claim containing such introduced claim recitation toembodiments containing only one such recitation, even when the sameclaim includes the introductory phrases “one or more” or “at least one”and indefinite articles such as “a” or “an” (e.g., “a” and/or “an”should be interpreted to mean “at least one” or “one or more”); the sameholds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, such recitation can mean atleast the recited number (e.g., the bare recitation of “tworecitations,” without other modifiers, means at least two recitations,or two or more recitations). Furthermore, in those instances where aconvention analogous to “at least one of A, B, and C, etc.” is used, ingeneral such a construction would include but not be limited to systemsthat have A alone, B alone, C alone, A and B together, A and C together,B and C together, and/or A, B, and C together, etc.). In those instanceswhere a convention analogous to “at least one of A, B, or C, etc.” isused, in general such a construction would include but not be limited tosystems that have A alone, B alone, C alone, A and B together, A and Ctogether, B and C together, and/or A, B, and C together, etc.). Anydisjunctive word or phrase presenting two or more alternative terms,whether in the description, claims, or drawings, can contemplate thepossibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” includes the possibilitiesof “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, the disclosure is also described in terms ofany individual member or subgroup of members of the Markush group.

Any ranges disclosed herein also encompass any and all possiblesubranges and combinations of subranges thereof. Any listed range can beeasily recognized as sufficiently describing and enabling the same rangebeing broken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. Language such as “up to,” “at least,” “greater than,” “less than,”and the like include the number recited and refer to ranges which can besubsequently broken down into subranges as discussed above. Finally, arange includes each individual member.

One or more or any part thereof of the techniques described herein canbe implemented in computer hardware or software, or a combination ofboth. The methods can be implemented in computer programs using standardprogramming techniques following the method and figures describedherein. Program code is applied to input data to perform the functionsdescribed herein and generate output information. The output informationis applied to one or more output devices such as a display monitor. Eachprogram may be implemented in a high level procedural or object orientedprogramming language to communicate with a computer system. However, theprograms can be implemented in assembly or machine language, if desired.In any case, the language can be a compiled or interpreted language.Moreover, the program can run on dedicated integrated circuitspreprogrammed for that purpose.

Each such computer program can be stored on a storage medium or device(e.g., ROM or magnetic diskette) readable by a general or specialpurpose programmable computer, for configuring and operating thecomputer when the storage media or device is read by the computer toperform the procedures described herein. The computer program can alsoreside in cache or main memory during program execution. The analysis,preprocessing, and other methods described herein can also beimplemented as a computer-readable storage medium, configured with acomputer program, where the storage medium so configured causes acomputer to operate in a specific and predefined manner to perform thefunctions described herein. In some embodiments, the computer readablemedia is tangible and substantially non-transitory in nature, e.g., suchthat the recorded information is recorded in a form other than solely asa propagating signal.

In some embodiments, a program product may include a signal bearingmedium. The signal bearing medium may include one or more instructionsthat, when executed by, for example, a processor, may provide thefunctionality described above. In some implementations, signal bearingmedium may encompass a computer-readable medium, such as, but notlimited to, a hard disk drive, a Compact Disc (CD), a Digital Video Disk(DVD), a digital tape, memory, etc. In some implementations, the signalbearing medium may encompass a recordable medium, such as, but notlimited to, memory, read/write (R/W) CDs, R/W DVDs, etc. In someimplementations, signal bearing medium may encompass a communicationsmedium such as, but not limited to, a digital or an analog communicationmedium (e.g., a fiber optic cable, a waveguide, a wired communicationslink, a wireless communication link, etc.). Thus, for example, theprogram product may be conveyed by an RF signal bearing medium, wherethe signal bearing medium is conveyed by a wireless communicationsmedium (e.g., a wireless communications medium conforming with the IEEE802.11 standard).

Any of the signals and signal processing techniques may be digital oranalog in nature, or combinations thereof.

While certain embodiments of this disclosure have been particularlyshown and described with references to preferred embodiments thereof,various changes in form and details may be made therein withoutdeparting from the scope of the disclosure.

What is claimed is:
 1. A neurological lead, comprising: a planar formed,cylindrical film coupled with an external tube, the planar formed,cylindrical film comprising: a plurality of electrodes, each electrodeof the plurality of electrodes having at least one rounded corner; and aplurality of periphery traces defined along the planar formed,cylindrical film, each periphery trace of the plurality of peripherytraces at least partially encircling a perimeter of a correspondingelectrode of the plurality of electrodes and electrically coupled withthe corresponding electrode.
 2. The neurological lead of claim 1,comprising: the at least one rounded corner of each electrode of theplurality of electrodes to decrease at least one focal point of currentdensity on the electrode.
 3. The neurological lead of claim 1,comprising: the at least one rounded corner of each electrode of theplurality of electrodes to protect the electrode from degradation. 4.The neurological lead of claim 1, comprising: each periphery trace ofthe plurality of periphery traces electrically coupled with at least twoconnection points, the at least two connection points positioned alongthe perimeter of the corresponding electrode to define at least twocorresponding regions in the corresponding electrode to distributeelectrical potential.
 5. The neurological lead of claim 1, comprising: aplurality of traces defined along the planar formed, cylindrical film,each trace of the plurality of traces electrically coupled with acorresponding periphery trace of the plurality of periphery traces via aconnection point.
 6. The neurological lead of claim 1, comprising: aplurality of tabs distributed along the planar formed, cylindrical film;and at least one of the plurality of electrodes disposed on each of theplurality of tabs.
 7. The neurological lead of claim 1, comprising: aplurality of ribbon cables distributed along the planar formed,cylindrical film, each ribbon cable of the plurality of ribbon cablesarranged between a pair of the plurality of electrodes.
 8. Theneurological lead of claim 1, comprising: a plurality of contactsdefined along the planar formed, cylindrical film, each contactelectrically coupled with a corresponding periphery trace of theplurality of periphery traces.
 9. A neurological lead, comprising: aplanar formed, cylindrical film coupled with an external tube, theplanar formed, cylindrical film comprising: a first insulative layer; afirst metallic layer mechanically coupled with the first insulativelayer, the metallic layer including a plurality of periphery traces; anda second metallic layer mechanically coupled with the first insulativelayer and with the first metallic layer, the second metallic layerincluding a plurality of rounded electrodes, each rounded electrode ofthe plurality of rounded electrodes at least partially surrounded by acorresponding periphery trace of the plurality of periphery traces andelectrically coupled with the corresponding periphery trace.
 10. Theneurological lead of claim 9, comprising: each rounded electrode of theplurality of rounded electrodes of the second metallic layer to decreasefocal points of current density on the rounded electrode.
 11. Theneurological lead of claim 9, comprising: a plurality of connectionpoints on the first metallic layer positioned along a perimeter of acorresponding rounded electrode of the plurality of rounded electrodesto define a plurality of regions in the corresponding rounded electrodeto distribute electrical potential among the plurality of regions in thecorresponding rounded electrode.
 12. The neurological lead of claim 9,comprising: the planar formed, cylindrical film including a barrierlayer disposed between the first metallic layer and the second metalliclayer, the barrier layer defining a plurality of vias to pass aplurality of connection points electrically coupling the correspondingperiphery trace with one of the plurality of rounded electrodes.
 13. Theneurological lead of claim 9, comprising: the first metallic layer ofthe planar formed, cylindrical film including a plurality of traces,each trace of the plurality of traces electrically coupled with one ofthe plurality of periphery traces via a connection point.
 14. Theneurological lead of claim 9, comprising: a plurality of ribbon cablesarranged between a pair of the plurality of rounded electrodes.
 15. Amethod of forming neurological leads, comprising: forming a film,comprising: a plurality of electrodes, each electrode of the pluralityof electrodes having at least one rounded corner; and a plurality ofperiphery traces, each periphery trace of the plurality of peripherytraces at least partially encircling a perimeter of a correspondingelectrode of the plurality of electrodes; and molding the film into acylinder, the cylinder defining a lumen.
 16. The method of claim 15,comprising: depositing an insulative layer to support the plurality ofperiphery traces; depositing a metallic layer on the insulative layer;and etching the metallic layer to form the plurality of periphery tracesalong the film.
 17. The method of claim 15, comprising: depositing abarrier layer to separate the plurality of periphery traces from theplurality of electrodes; forming a plurality of vias through the barrierlayer; and depositing a metallic layer on the barrier layer; etching themetallic layer to form the plurality of electrodes along the film and toform at least two connection points through the plurality of vias toelectrically couple with the plurality of electrodes.
 18. The method ofclaim 15, comprising: forming the film comprising at least twoconnection points positioned along the perimeter of the correspondingelectrode to define at least two corresponding regions in thecorresponding electrode to distribute electrical potential.
 19. Themethod of claim 15, comprising: forming the film comprising a pluralityof ribbon cables distributed along the film, each ribbon cable of theplurality of ribbon cables arranged between a pair of the plurality ofelectrodes.
 20. The method of claim 15, comprising: forming the filmcomprising a plurality of traces defined along the film, each trace ofthe plurality of traces electrically coupled with a correspondingperiphery trace of the plurality of periphery traces.